Synergistic additive mixture



United States Patent 3,425,815 SYNERGISTIC ADDITIVE MIXTURE Robert H. Rosenwald, Western Springs, and Russell F.

Stedman and James C. Hughes, Des Plaines, Ill., as-

signors to Universal Oil Products Company, Des

Plaines, Ill., a corporation of Delaware No Drawing. Filed May 7, 1965, Ser. No. 454,167 US. CI. 44-72 8 Claims Int. Cl. C101 1/26, 1/22 This invention relates to a novel additive composition comprised of a mixture of components which synergistically function to produce improved results beyond the results which would be expected from the use of the components individually.

The novel additive mixture is used in fuels supplied to carbureted internal combustion engines. For example, a serious problem in the operation of automobiles is stalling of the engine due to the formation of ice in the carburetor throttle body and on the throttle plate. As is well known, at temperatures ranging from about 30 to about 60 F. the periods of relatively high humidities, such stalling has been encountered under idling or low load conditions. This is caused by the air-borne moisture undergoing freezing due to the refrigerating effect encountered in normal fuel vaporization Within the carburetor. The ice formed on the throttle plate and adjacent carburetor walls restricts the narrow air Openings and causes engine stalling.

The icing problem is of increasing importance because of the design of newer automobiles. For example,

present cars do not have a manual throttle and therefore the operator of the car is no longer able to increase the idle speed during the warm up period to prevent such stalling. Furthermore, the increasing use of automatic transmissions adds to this problem becauuse the idle speed must be kept low to avoid creeping and, accordingly, the idle speed is not sufficiently fast to avoid stalling due to icing. Still another development which appears to add to this problem is the increased volatility of commercial gasolines, as it has been found that more frequent stalling is encountered with the more volatile fuels.

Another problem in the operation of carbureted combustion engines is the formation of deposits on the walls of the carburetor. In time such deposit formation could interfere with the proper operation of the throttle plate and/or plug the small idle passages and cause stalling of the engine or other undesired effects. This is particularly acute in the case of taxicabs or the like where the engine is allowed to idle for considerably long periods of time. Under such long idling conditions, impurities contained in the fuel or entering from the atmosphere may deposit on the walls of the carburetor and interfere with proper operation thereof. Anti-smog crankcase ventilating systems wherein the crankcase 'blowby gases are routed through the carburetor air cleaner and thence through the carburetor, to be ultimately consumed in the engine, greatly aggravate the formation of carburetor deposits.

The oil industry is well aware of these problems and numerous additives have been proposed and used to avoid these difliculties. Generally, a specific additive is used for each problem. For example, an alcohol type deicer is used to lower the freezing point of the water and to dissolve and remove water droplets. Various phosphate salts of amines have been proposed for use as additives for gasoline but, here again, a specific type of phosphateamine salt has been proposed for a specific purpose.

Surprisingly it now has been found that a mixture of certain phosphate salts of two different types of amines functions synergistically to improve both the deicing properties and the detergent properties of the fuel beyond that which would be expected by the use of either of these phosphate salts separately. This would not be predicted because it would not be expected that combining an additive which has poor or only moderate anti-icing properties with another additive which has somewhat better anti-icing properties would result in a blend which possesses extremely better anti-icing properties. Similarly, it would not be expected that combining an additive of low or moderate detergent properties with a different additive of better detergent properties would result in a blend having exceedingly better detergency properties. As will be shown by the examples appended to the present specifications, the blend of the present invention produces this synergistic effect. This surprising improvement in both deicing and detergency properties may be considered as a double synergistic effect.

The mechanism by which the blend functions synergistically is not understood and, undoubtedly, is of a complicated nature. This is further illustrated by the fact that anti-icers and detergents, even when used separately, vary in their effectiveness in different gasolines. Similarly, the blend of the present invention will be more effective in some gasolines than in others. This must be tied in somewhat to the chemical and perhaps physical nature of the gasoline itself.

In one embodiment the present invention relates to a method of preventing stalling due to icing and of main taining carburetor cleanliness of a carbureted combustion engine which comprises supplying to said engine a hydrocarbon fuel containing a synergistic mixture of a phosphate salt of an N-alkyl-diaminoalkane and a phosphate salt of an alkyl-monoamine.

It is believed that such a mixture of salts also is a new composition of matter and accordingly the same is being claimed as such in the present application.

From the hereinbefore set forth embodiment, it will be noted that the novel blend of the present invention comprises a mixture of a phosphate salt of an N-alkyldiaminoalkane and a phosphate salt of an alkyl-monoamine. As hereinbefore set forth, each of these types of salts has been proposed separately for use as additives to gasoline. However, it is surprising that a mixture of these phosphate salts of amines, which may be considered as somewhat related chemically, would produce results, both as to anti-icing and as to detergency, exceedingly beyond the results obtained by using either of these salts separately.

In a preferred embodiment the phosphate salt is an alkyl phosphate salt. Any suitable alkyl phosphate is used in preparing the amine salts and may be the: same or different in preparing the diamine salt and the monoamine salt. The a-lkyl acid phosphate includes both the alkyl acid orthophosphates and the alkyl acid pyrophosphates. In the alkyl acid orthophosphates, the mono-alkyl ester, dialkyl ester or a mixture thereof may be employed. In the alkyl acid pyrophosphates, the monoalkyl ester, dialkyl ester, trialkyl ester or mixtures thereof may be employed, the dialkyl ester being preferred, and the ester groups may be attached to the same or different phosphorus atom. Generally, however, this compound will be symmetrical and, thus, the alkyl ester groups will be attached to different phosphorus atoms.

Illustrative examples of preferred alkyl acid orthophosphate and pyrophosphates are set forth below. In general, it is preferred that alkyl moiety contains from about 3 to about '20 and more particularly from about 4 to about 15 carbon atoms each. Accordingly, particularly preferred alkyl acid orthophosphates include monobutyl acid orthophosphate, dibutyl acid orthophosphate, mixture of monoand dibutyl acid orthophosphates, monopentyl acid orthophosphate, dipentyl acid orthophosphate, mixture of monoand dipentyl acid orthophosphates, monohexyl acid orthophosphate, dihexyl acid orthophasphate, mixture of monoand dihexyl acid orthophosphates, monoheptyl acid orthophosphate, diheptyl acid orthophosphates, mixture of monoand diheptyl acid orthophosphates, monooctyl acid orthophosphate, dioctyl acid orthophosp'hate, mixture of monoand dioctyl acid orthophosphates, mononyl acid orthophosphate, dinonyl acid orthophosphate, mixture of monoand dinoyl acid orthophosphates, monodecyl acid orthophosphate, didecyl acid orthophosphate, mixture of monoand didecyl acid orthophosphates, monoundecyl acid orthophosphate, diundecyl acid orthophosphates, monododecyl acid orthophosphate, didodecyl acid orthophosphate, mixture of monoand didodecyl acid orthophosphates, monotridecyl acid orthophosphate, ditridecyl acid orthophosphate, mixture of monoand ditridecyl acid orthophosphates, monotetradecyl acid orthophosphate, ditetradecyl acid ort-hophosphate, mixture of monoand ditetradecyl acid orthophosphates, monopentadecyl acid orthophosphate, dipentadecyl acid orthophosphate, mixture of monoand dipentadecyl acid orthophosphates, etc. It is understood that the alkyl moiety may be of straight or branched chain and that it may be of primary, secondary or tertiary configuration.

Preferred alkyl acid pyrophosphates include monobutyl acid pyrophosphate, dibutyl acid pyrophosphate, mixture of monoand dibutyl acid pyrophosphate, monopentyl acid pyrophosphate, dipentyl acid pyrophosphate, mixture of monoand dipentyl acid pyrophosphates, monohexyl acid pyrophosphate, dihexyl acid pyrophosphate, mixture of monoand dihexyl acid pyrophosphates, monoheptyl acid pyrophosphate, diheptyl acid pyrophosphate, mixture of monoand diheptyl acid pyrophosphates, monooctyl acid pyrophosphate, dioctyl acid pyrophosphate, mixture of monoand dioctyl acid pyrophosphates, monononyl acid pyrophosphate, dinonyl acid pyrophosphate, mixture of monoand dinonyl acid pyrophosphates, monodecyl acid pyrophosphate, didecyl acid pyrophosphate, mixture of monoand didecyl acid pyrophosphates, monoundecyl acid pyrophosphate, diundecyl acid pyrophosphate, mixture of monoand diundecyl acid pyrophosphates, monododecyl acid pyrophosphate, didodecyl acid pyrophosphate, mixture of monoand didodecyl acid pyrophosphates, monotridecyl acid pyrophosphate, ditridecyl acid pyrophosphate, mixture of monoand ditridecyl acid pyrophosphates, monotetradecyl acid pyrophosphate, ditetradecyl acid pyrophosphate, mixture of monoand ditetradecyl acid pyrophosphates, monopentadecyl acid pyrophoshate, dipentadecyl acid pyrophosphate, mixture of monoand dipentadecyl acid pyrophosphates, etc. Here again, it is understood that the alkyl moiety may be of straight or branched chain and may be of primary, secondary or tertiary configuration.

The specific phosphates hereinbefore set forth are preferred. It is understood that other suitable alkyl phosphates may be used in accordance with the present invention. For example, alkyl acid phosphates, including both the orthoand pyrophosphates, are manufactured commercially as a mixture of monoand dialkyl acid phosphates and are available commercially at a considerably lower cost. In many cases, such mixtures are very suitable for use in preparing the salt of the present invention and such use, therefore, is preferred for economic reasons.

While the alkyl acid phosphates are preferred, it is understood that other suitable phosphates may be employed but not necessarily with equivalent results. For example, in place of thealkyl moiety of the phosphate, an unsaturated aliphatic group may be employed, and thus may contain a double bond in the aliphatic chain, In still another embodiment, the alkyl moiety or moieties may be replaced by cyclic derivatives including particularly cyclohexyl, but may comprise cyclobutyl, cyclopentyl, cycloheptyl,

cyclooctyl, etc. It is understood that the aliphatic or cyclic groups may contain hydrocarbyl or non-hydrocarbyl substituents attached thereto, the last mentioned being selected from hydroxy, alkoxy, etc.

Any suitable alkyl monoamine is used in preparing the alkyl phosphatesalt of alkyl monoamine for use as one component of the additive mixture of the present invention. The alkyl monoamine may contain from about 3 to about 20 carbon atoms and preferably contains from about 4 to about 12 carbon atoms and thus includes butyl amine, pentyl amine, hexyl amine, heptyl amine, octyl amine, nonyl amine, decyl amine, undecyl amine, dodecyl amine, etc. It is understood that the alkyl moiety may be of straight or branched chain and may be of primary, secondary or tertiary configuration. A particularly preferred alkyl monoamine for use in the present invention is 2-ethylhexyl amine. Other preferred alkyl monoamines include those known as beta amines in which the alkyl group is attached to the nitrogen atom through the beta carbon atom of the alkyl group.

Any suitable diamine is used in preparing the alkyl phosphate salt for use as a component in the additive mixture of the present invention. While the diamine may contain from about 3 to about 40 carbon atoms, it preferably contains from about 8 to about 20 carbon atoms. A particularly preferred diamine is N-alkyl diaminoalkane in which the alkyl moiety contains from about 3 to about 30 carbon atoms and more particularly from about 6 to about 20 carbon atoms and the alkane moiety contains from about 2 to about 12 carbon atoms and preferably from about 3 to about 6 carbon atoms. A particularly preferred N-alltyl diaminoalkane is N-alkyl-l,3- diaminopropane, the alkyl group being derived from tallow. This compound is available commercially under the trade name of Duomeen T. Other preferred N-alkyl- 1,3-diaminopropanes comprise those in which the alkyl group is derived from lauric acid, coconut fatty acid, soya fatty acid, etc. These are available commercially at the present time and comprise mixed alkyl-substituted 1,3- diaminopropanes. For example, in the case of Duomeen T the alkyl group contains from about 12 to 20 carbon atoms per group and mostly contain 16 to 18 carbon atoms. However, when desired, the alkyl group of the N-alkyl-1,3-diaminopropanes or other N-alkyl-diaminoalkanes may be prepared to contain any number of carbon atoms desired in the alkyl group and, thus, is selected from hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, etc. It is understood that a mixture of diamines containing different alkyl groups may be employed and that the alkyl and alkane moieties may be of straight or branched chain. Furthermore, it is understood that the alkyl moiety may be of primary, secondary or tertiary configuration. Also, particularly preferred in this embodiment are the beta amines in which the alkyl groups are attached to the nitrogen atoms through the beta carbon atoms of the alkyl groups.

While the N-alkyl-1,3-diamin0propanes are preferred it is understood that other suitable N-alkyl diaminoalkanes may be employed. Illustrative examples include N-alkyl-1,2 diaminoethanes, N-alkyl-l,2 diaminopropanes, N-alkyl-l,Z-diaminobutanes, N-alkyl-l,3-diaminobutanes, N-alkyl-l,4-diaminobutanes, N-alkyl-1,2-diaminopentanes, N-alkyl-1,3-diaminopentanes, N-alkyl-l,4-diaminopentanes, N-alkyl-1,5-diaminopentanes, N-alkyl- 1,2-dia-minohexanes, N-alkyl-l,3-diaminohexanes, N-alkyl-1,4-diaminohexanes, N-alkyl-1,5-diaminohexanes, N- alkyl-1,6-diaminohexanes, etc.

In another embodiment the alkyl-monoamine and/or alkyl-diaminoalkane may contain a double bond in the alkyl group. In still another embodiment the alkyl group may contain non-hydrocarbyl substitutions, the substitutions being selected from hydroxy, alkoxy, N-dihydrocarbylamide, halogen, particularly chlorine and fluorine, etc. In still another embodiment, in place of an aliphatic group, the amine may be a cyclic amine as, for example, cyclohexyl amine, dicyclohexyl amine, and cyclohexyldiaminoalkane or the cycloalkyl group may be cyclobutyl, cyclopentyl, cycloheptyl, cyclooctyl, etc. In still another embodiment the cyclic group may be a heterocyclic nitrogen compound including piperidyl, piperazyl, etc. It is understood that the different amines are not necessarily equivalent.

In general the neutral salts of the alkyl phosphate and alkyl monoamine and of the alkyl phosphate and diamine are preferred. The neutral salts are prepared by utilizing stoichiometric amounts of the acid and the amine. In other words, the concentration of the alkyl acid phosphate and of the alkyl monoamine or of the alkyl acid phosphate and of the diaminoalkane will be selected so that there will be an equivalent number of acid groups to amino groups. Thus, the specific concentrations will depend upon whether the orthophosphate or pyrophosphate or whether the monoalkyl phosphate or dialkyl phosphate are used. It also will depend upon whether the monoamine or diamine is employed. In another embodiment the salt is a basic salt which is prepared by utilizing a deficiency of acid groups in relation to the amino groups. In still another embodiment the acid salt is used, which is prepared by using an excess of acid groups with relation to the amine groups. It is understood that these different salts are not necessarily equivalent. From the above description it will be seen that a number of different salts may be used in accordance with the present invention. It is understood that these different salts are not necessarily equivalent in the same fuel but all of them will serve to give in most, if not all, fuels improved results over those obtained through the use of each of the components individually.

The salts are prepared in any suitable manner and in general, are prepared by mixing the alkyl phosphate and the alkyl monoamine and/or diaminoalkane in the required proportions at ambient temperature, preferably with vigorous stirring. When desired the phosphate salt of the monoamine and the phosphate salt of the diamine may be separately prepared and utilized as such or subsequently mixed to prepare a blended composition. In another embodiment the mixture of salts may be prepared simultaneously by reacting the alkyl phosphate or phosphates with both the =monoamine and diamine in the re quired proportions to form the mitxure of salts in one step.

The salts .are readily prepared at room temperature, although slightly elevated temperature which generally will not exceed about 200 F. may be employed when desired. Excessive temperatures should not be allowed in order to avoid the undesired formation of reaction products resulting in the liberation of water and in the formation of phosphor amidic acid derivatives or other undesired reaction products. When desired, it may be of advantage to utilize a solvent, either in forming a more fluid mixture of the acid and/ or amines before mixing or during the mixing thereof. In some cases it is desirable to admix the salt or salts with a solvent in order to form a more fluid final product. Any suitable solvent may be used and generally will comprise an organic compound and more particularly a hydrocarbon distillate. Particularly preferred solvents are aromatic hydrocarbons including benzene, toluene, xylene, ethylbenzene, cumene, etc., or mixtures thereof, or parafiinic hydrocarbons including pentane, hexane, heptane, octane, nonane, decane, etc., or mixtures thereof, or mixtures of the aromatic and paraffinic hydrocarbons.

As hereinbefore set forth, the phosphate salt of monoamine and the phosphate salt of diamine may be prepared separately or in admixture. When prepared separately, the salts may be blended to form an additive composition or the salts may be added separately to the substrate. The different salts will be used in a proportion to produce improved anti-icing and detergency. This may range from 5% to 95% of one salt and 5% to 95% by weight of the other salt. [n some cases it is preferred that the phosphate salt of the diamine is used in a larger proportion and, in such cases, the salt of the diamine is used in a concentration of from about 60% to about by Weight and the phosphate salt of the monoamine is used in a concentration of from about 10% to about 40% by Weight, exclusive of solvent. When a solvent is employed, a stock solution may be prepared to contain the active ingredients in a concentration of from about 10% to a saturated solution which will be above 50% by weight of active ingredients.

The amount of the additive composition or the total of the two salts when added separately to gasoline or other carbureted engine fuel will be sufficient to effect improved deicing and improved detergency. For economic reasons the concentration should be as low as practical and thus may range from 0.001% up to 0.05% by weight and preferably is within the range of from about 0.00Q% to about 0.01% by weight of the fuel, based on active ingredients.

As hereinbefore set forth, each of the salts may be added separately to the fuel or preferably are formed as a blend in a suitable solvent and incorporated in the fuel in this manner, preferably with intimate mixing to obtain uniform distribution throughout the fuel. It is understood that the mixture of salts of the present invention may be used along with other additives; added to the fuel for specific purposes including, for example, antioxidants, metal deactivators, etc. When desired, these other additives may be blended with the salts of the present invention and the mixture marketed as a single commodity of multiple purposes. As an additional. advantage of the salts of the present invention, these salts also serve to retard corrosion of the automotive parts through which the gasoline passes. Still another advantage to the present invention is in the detergent action being effective to some degree beyond the carburetor, thus resulting in a cleaner intake manifold and less deposit on the intake valves.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

Example I The additive mixture of this example comprises 75% by weight of the mixed monoand diiszooctyl acid orthophosphate salts of N-tallow-1,3-diaminapropane and 25% by weight of the mixed monoand ditridecyl acid orthophosphate salts of Z-ethylhexyl amine. These salts were each separately prepared by intimately mixing the phosphates and amines in proportions to form the neutral salts and then blending them with xylene solvent to form a final solution containing the active ingredients in a concentration of 50% by Weight.

In order to carefully follow the deicing and detergent properties of the additives, it has been decided to evaluate each of these properties separately. In other words, a series of evaluations were made in which the deicing properties of the gasoline were determined and another series of evaluations were made in which the detergency properties were determined. The deicing evaluations were made in a standard CFR engine operated at a compression ratio of 5.5 to 1 and a speed of 900 rpm. The standard carburetor was replaced by an insulated glass throttle section so that the formation of ice could be observed 'visually. The entire carburetor was installed in a Plexiglass chamber so that the external surfaces of the carburetor were at the same temperature as the air intake. A Dry Ice container was maintained one-half full at all times and was attached to the canburetor bowl in order to maintain constant fuel temperature and to prevent the loss of light ends of the fuel. A surge chamber of a volume approximately equal to the cylinder displacement Was installed between the carburetor and the engine, with the manifold vacuum being controlled by a valve ahead of the surge chamber. Saturated air was obtained by passing the air through a modified CFR ice tower and thence over a water sump. The temperature of the water in the sump could be controlled so that saturated air at the temperature of the water results. The air was pressurized to approximately 3.0 inches water to insure positive flow through the tower. The saturated air temperature was varied in 25 F. increments to determine the temperature producing the maximum icing condition, which was measured on the basis of minimum time for the manifold vacuum to increase from 9.2 to 11.0 inches of mercury. It was established previously that a manifold vacuum of 11.0 inches of mercury was equivalent to a stall. The tests were run at a temperature of 5 less than the maximum icing temperature.

The data in the following table report the results obtained when using a regular grade commercial gasoline having a boiling range of from 96 to 382 F., on API gravity at 60 F. of 61.1 and a Reid vapor pressure of 10.7 p.s.i. In this series of evaluations, control samples of the gasoline, samples of the gasoline containing each of the salts separately, and samples of the gasoline containing the blend of 75 of the phosphate salt of diaminoalkane and 25 of the phosphate salt of ethylhexyl amine, prepared as described above, were evaluated. The results in the following table are the average of three runs for each of the evaluations.

TABLE I Time to stall, seconds Additive Concentration,

p.p.m.

From the data in the above table it will be seen that the mixture of the two phosphate salts considerably increased the time to stalling far beyond that which would be expected from the use of each of these salts separately. As hereinbefore set forth, because the different phosphate salts of amines are somewhat related chemically, it would not be predicted that the mixture would be any different from the use of the salts separately. However, at all of the concentrations shown in the above table, the increase was most surprising. At best it would have been expected that the results obtained when using the mixture would be the average obtained by each of the additives separately. For example, in the case of the use at 25 parts per million, the expected time would be the average of 9.8 and 12.8, or 11.3 seconds but instead, surprisingly, the blend resulted in a time of 62.4 seconds. Similarly, at 100 parts per million concentration, the expected time would be the average of 27 and 46, or 37 seconds but instead was 152.1 seconds.

A separate base run was made for each series of additives as will be noted. The silent variation in time for. the base gasoline is within the normal variation for this test procedure.

Example II The detergency properties of the additives were evaluated in a six cylinder Chevrolet 235 engine in which the standard cast iron caburetor throttle body was replaced by a section of transparent Plexiglas tubing upon which deposits form and can be inspected visually and, when desired, can be photographed. The carburetor air is supplied from the room through an air cleaner and inducted into the air stream along with heated blowby and a small amount of exhaust gas. The engine is operated for five hours on a speed cycle of two minutes at 500 rpm. and one minute at 1500 rpm. all with no load. As hereinbefore set forth, deposit formation occurs on the throttle body. The throttle body is inspected visually and the results are reported as very dirty, dirty, moderate and clean. The very dirty designation indicates that the throttle body is very heavily coated on the inside. The dirty designation indicates heavy coating. The designation of moderate means that there is a definite but lesser coating. The designation of clean indicates that there is very little deposit coating on the throttle body.

The evaluations of this example were made using a gasoline having a boiling range of from 124 to 424 F., an API graivty at 60 F. of 54.5 and a Reid vapor pressure of 5.1 p.s.i. The following table reports evaluations made in the manner described above when using samples of the gasoline without additive, samples of the gasoline containing the phosphate salt of the monoamine, samples of the gasoline containing the phosphate salt of diaminoalkane, and samples of the gasoline containing the mixture of phosphate salts described in Example I. In all cases the additives, when employed, were used in a concentration of 50 parts per million of the 50% solution. In the case of the blend, the toal concentration of active ingredients was 25 parts per million.

diisooctyl acid phophate salts of N-tallow-1,3- diaminopropane and 25% by weight of mixed monoand ditridecyl acid phosphate salts of 2-ethylhexyl amine.

Here again it is surprising that the mixture of phosphate salts resulted in the considerable reduction of the deposit formation. Normally it would be expected that the results would be the average of each of the individual components. Certainly it would be predicted that the use of additives which gave moderate and dirty ratings would result in a rating of clean.

Example III The blend of this example is a mixture of 75% by weight of the mixed monoand ditridecyl acid phosphate salts of N-tallow-1,3-diaminopropane and 25% by weight of mixed monoand ditridecyl acid phosphate salts of n-heptyl-beta amine. In the monoamine the carbon atoms are in straight chain arrangement and the amino nitrogen is attached to the beta or second carbon atom. These salts were separately prepared in substantially the same manner as described in Example I and then formed as a 50% solution of active ingredients in xylene solvent.

When evaluated in another sample of the gasoline and in the same manner as described in Example II, the blend of 75% by weight of the mixed monoand ditridecyl acid phosphate salts of N-tallow-l,S-diaminopropane and 25 by weight of the mixed monoand ditridecyl acid phosphate salts of the beta-heptyl amine, in a concentration of 50 parts per million in the 50% solution, resulted in clean carburetor throttle bodies. This is in contrast to the very dirty throttle bodies obtained when using the gasoline samples without additives or the moderate results obtained when using the samples containing only the phosphate salt of the diaminoalkane and the slightly better results when using the samples containing only the phosphate salt of the beta-amine. Here again, a synergistic effect is observed when using the mixture of the phosphate salts of the difierent amines.

9 Example IV The additive blend of this example is a mixture of 25% by weight of the mixed monoand ditridecyl acid phosphate salts of N-tallow-1,3-diaminopropane and 75% by Weight of the mixed monoand ditridecyl acid phosphate salts of n-heptyl-beta amine.

When evaluated in another sample of the gasoline in the same manner as described in Example II, in a concentration of 25 parts per million, the carburetor throttle body was rated clean. Here again, the synergistic effect of the mixture is demonstrated.

Example V The salt of this example is a blend of 60% by weight of the diamyl acid phosphate salt of N-oleyl-l,3-diaminopropane and 40% by weight of diamyl acid phosphate salt of oleyl amine. The salt was prepared by intimately mixing at room temperature two equivalents of the diamyl acid phosphate with one equivalent each of N- oleyl-1,3-diaminopropane and oleyl amine. Toluene solvent was used in the mixing in a concentration to form a final solution of 40% by weight of active ingredients.

The blended additive mixture solution, prepared as described in the above manner, is incorporated in commercial gasoline in a concentration of 60 parts per million and serves to prevent engine stalling and to maintain cleanliness of the carburetor throttle body.

We claim as our invention:

1. A synergistic mixture of from about to about 95% by weight of an alkyl phosphate salt of an N-alkyldiaminoalkane and from about 5% to about 95% by weight of an alkyl phosphate salt of an alkyl-monoamine.

2. A synergistic mixture of from about 5% to about 95% by weight of an alkyl phosphate salt of N-alkyl- 1,3-diaminopropane and from about 5% to about 95% by weight of an alkyl phosphate salt of an alkylmonoamine.

3. A synergistic mixture of from about 5% to about 95% by weight of mixed monoand dialkyl phosphate salts of N-tallow-l, 3-aminopropane and from about 5% to about by weight of mixed monoand dialkyl phosphate salts of alkyl-monoamine.

4. A synergistic mixture of from about 5% to about 95 by Weight of mixed monoand dioctyl acid phosphate salts of N-tallow-1,3-diaminopropane and from about 5% to about 95 by weight of mixed monoand dioctyl acid phosphate salts of alkyl-monoamine.

S. A synergistic mixture of from about 5% to about 95% by weight of mixed monoand ditridecyl phosphate salts of N-tallow-1,3-diaminopropane and from about 5% to about 95 by weight of mixed monoand ditridecyl phosphate salts of alkyl-monoamine.

6. A synergistic mixture of from about 5% to about 95% by weight of mixed monoand ditridecyl phosphate salts of N-tallow-1,3-diaminopropane and from about 5% to about 95% by weight of mixed monoand ditridecyl phosphate salts of ethylhexyl amine.

7. A synergistic mixture of from about 5% to about 95% by weight of mixed monoand ditridecyl acid phosphate salts of N-tallow-1,3-diaminopropane and from about 5% to about 95 by weight of mixed monoand ditridecyl phosphate salts of beta-alkyl amine.

8. A synergistic mixture of from about 5% to about 95% by weight of mixed monoand ditridecyl acid phosphate salts of N-tallow-1,3-diaminopropane and from about 5% to about 95 by weight of mixed monoand ditridecyl phosphate salts of beta-heptyl amine.

References Cited UNITED STATES PATENTS 2,848,414 8/1954 Chenicek 44--72 2,863,742 12/1958 Cantrell et 211. 2,863,904 12/1958 Cantrell et al. 3,063, 820 11/ 1962 Chenicek.

DANIEL E. WYMAN, Primary Examiner. Y. H. SMITH, Assistant Examiner.

US. Cl. X.R. 44-56 

1. A SYNERGISTIC MIXTURE OF FROM ABOUT 5% TO ABOUT 95% BY WEIGHT OF AN ALKYL PHOSPHATE SALT OF AN N-ALKYLDIAMINOALKANE AND FROM ABOUT 5% TO ABOUT 95% BY WEIGHT OF AN ALKYL PHOSPHATE SALT OF AN ALKYL-MONOAMINE. 